Implements the
Laguerre's Method for root finding of real coefficient polynomials.
For reference, see
A First Course in Numerical Analysis
ISBN 048641454X, chapter 8.
Laguerre's method is global in the sense that it can start with any initial
approximation and be able to solve all roots from that point.
The algorithm requires a bracketing condition.

laguerre

Deprecated.This method should not be part of the public API: It will
be made private in version 4.0.

Find a real root in the given interval.
Despite the bracketing condition, the root returned by
LaguerreSolver.ComplexSolver.solve(Complex[],Complex) may
not be a real zero inside [min, max].
For example, p(x) = x3 + 1,
with min = -2, max = 2, initial = 0.
When it occurs, this code calls
LaguerreSolver.ComplexSolver.solveAll(Complex[],Complex)
in order to obtain all roots and picks up one real root.